In the conventional motor control device and motor control method, a switching mode of an inverter is determined so that a current that flows in a three-phase AC motor matches a command current, the inverter operates in the determined switching mode, and a voltage corresponding to the switching mode is applied to the three-phase AC motor, to thereby control the rotation of the three-phase AC motor.
As the above-mentioned motor control device and motor control method, there is a triangle wave comparison PWM control of the three-phase AC motor. This control method calculates a command voltage for each phase according to an error between a current command value and a current flowing in each phase, and determines the switching mode of the inverter on the basis of the calculated command voltage and a magnitude of carriers having a triangle waveform.
As a disclosure of a technique for improving a response of a current in the triangle wave comparison PWM control, for example, Patent Document 1 and Patent Document 2 have been known.
In a control method disclosed in Patent Document 1, future currents (torques) in all of the switching modes of the inverter are predicted with the use of a motor model on the basis of a current flowing in the motor, a magnetic pole position of a rotor, and a rotational speed of the rotor. Then, the control method selects any switching mode for generating the future current (torque) that minimizes the error relative to a current (torque) command value for controlling the motor, and drives the inverter in the switching mode.
Also, in Patent Document 2, predicted currents ide(n+1) and iqe(n+1) in one subsequent control cycle are calculated on the basis of a voltage vector (switching mode) V(n) of the existing inverter so that a controlled variable by a model prediction control disclosed in Patent Document 1 is predicted with higher precision. The predicted currents ide(n+1) and iqe(n+1) are set as defaults, and predicted currents ide(n+2) and iqe(n+2) in a further one subsequent control cycle are calculated for each voltage vector V(n+1). Then, a voltage vector V(n+1) in one subsequent control cycle is determined by an evaluation function J having the predicted currents ide(n+2) and iqe(n+2) as inputs so that the error relative to the command current becomes smallest.